Augmented reality (AR) technology is known in which when an image of a real-world object is displayed on a display, a content that does not exist in the real world is displayed in such a manner as to be overlaid on the image displayed on the display, so that a combined image in which the content appears as if it existed in the real world is provided. Hereinafter, this content is referred to as an “AR content”. It is possible for a user who views a combined image to acquire information displayed as an AR content and to catch more information than when the user directly views and recognizes the real world. Note that an AR content is sometimes image data that itself suggests a distinctive meaning by using its shape and color, and is sometimes image data including text data.
AR includes technologies called location-based AR and technologies called vision-based AR. The former acquires position information and information on bearings of a camera-equipped terminal from a global positioning system (GPS) sensor or the like and, in accordance with the position information and the bearing information, determines details of an AR content to be displayed in such a manner as to be overlaid and a position at which the AR content is to be displayed in such a manner.
The latter performs object recognition and space perception on image data acquired from a camera. Upon recognizing that image data is data of an image in which a specific object is captured, the vision-based AR displays an AR content corresponding to this specific object in such a manner as to be overlaid according to a space perception result (for example, Japanese Laid-open Patent Publication No. 2002-092647 and Japanese Laid-open Patent Publication No. 2004-048674). Note that AR in which a marker is an object to be recognized is sometimes referred to as “marker vision-based AR”, and AR in which an object other than a marker is an object to be recognized is sometimes referred to as “marker-less vision-based AR”.
Additionally, a technology is known in which, in a game machine including a vision-based AR function, when an imaging device included in the game machine captures an image of a marker, a selection object for menu selection is displayed on a display of the game machine (for example, Japanese Laid-open Patent Publication No. 2012-068984). Further, when the user tilts the game machine, and, as a result, the imaging direction of the imaging device crosses a collision region of the selection object, the game machine determines that the selection object has been selected.